Attaching conventional filters to a fisheye lens can be problematic due to the bulbous front element impeding a conventional screw-in filter or slot-in filter holder. 7Artisans has combated this problem by essentially re-releasing its existing FF 9mm f/5.6 ASPH in a variety of rather neat rear ND filter bundles.
Rear ND filters attach to the rear element that sits closest to the camera's sensor, completely mitigating a fisheye's spherical front optic. The previously available 7Artisans FF 9mm f/5.6 ASPH can now be purchased in three rear filter packages: an ND64 ($479), ND1000 ($479) and ND64/ND1000 ($499). An ND64 is a six-stop ND, while an ND1000 is a 10-stop ND filter, ideal for capturing long exposures.
